A modern communications system, for example, a GSM (Global System for Mobile Communications) system, a CDMA (Code Division Multiple Access) 2000/WCDMA (Wideband Code Division Multiple Access) system, and a 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) system, usually operates on a carrier frequency below 3 GHz. Generally multi-antenna technology is adopted to enhance system capacity and coverage or improve user experience. With emergence of intelligent terminals, especially, video services, current spectrum resources already hardly satisfy explosively growing capacity requirements of users. Currently, a high frequency band with a larger available bandwidth, especially, a millimeter wave band, increasingly becomes a candidate band in a next-generation communication system. On a basis of the multi-antenna technology, the high frequency band, especially, the millimeter wave band, can be used to reduce sizes of multi-antenna configurations, which facilitates site acquisition and multiple-antenna deployment. However, different from an operating band of an existing system such as LTE, the high frequency band will bring a larger path loss, and especially, a loss of radio propagation is further increased due to adverse impact of factors such as atmosphere and vegetation. Under this situation, a path loss caused by the high frequency band also affects transmission reliability of communication signal (for example, synchronization signal, control channel, and broadcast channel) in the existing communication system.